The invention relates to a reconfigurable digital logic unit comprising at least one logic gate with cells which have a magnetic layer system and the resistance of which can be altered by means of magnetic field pulses, which logic gate comprises at least one first line branch with at least one data cell and a second line branch—connected in parallel therewith—with at least one reference cell, and also a means for evaluating the resistances of the first and second line branches, said resistances representing a measure of the logic state of the logic gate.
Cells of this type make it possible to store items of information on a magnetic basis. The magnetization of a layer of the magnetic layer system can be changed by means of a magnetic field pulse, so that the magnetoresistance of this layer structure changes by a few per cent. The respective resistance can be read out and is a measure of the logic state of the cell.
However, the application possibilities for digital logic units of this type have been greatly restricted heretofore. One of the practical problems is that the TMR resistance (tunneling magnetoresistive) primarily depends on the current direction chosen. This is possibly caused by different materials on the two barrier sides.
DE 199 22 129 C1 describes a device for logically combining signals on a magnetoresistive basis. In this case, input signals present at inputs are combined to form fixed output signals present at one or a plurality of outputs. This involves fixed, invariable circuits which are neither reprogrammable nor reconfigurable.
A so-called analog reference cell is described in DE 102 37 876 A1. An analog reference cell is a component which supplies a certain standard resistance after the setting by corresponding means. The analog reference cell thus forms a component of a logic reference cell which can store a signal and can be set by means of a configuration signal.